護理師評估一位左前臂骨折、4 小時前剛打上石膏（plaster cast）的病人。哪一項評估發現需要護理師立即通知醫療提供者？

Option C is correct. Swelling inside a rigid cast raises pressure within the forearm compartments and can cause acute compartment syndrome. The earliest and most sensitive sign is pain that is out of proportion to the injury and is not relieved by prescribed analgesics or elevation; pain also increases with passive stretching of the fingers. The nurse must notify the provider immediately so the cast can be bivalved or removed and, if needed, a fasciotomy performed. Pallor, paresthesia, paralysis, pulselessness, and coolness are late signs that often indicate irreversible neuromuscular damage, so the nurse should not wait for them. Option A is incorrect because a capillary refill time of 2 seconds is within the normal range of 3 seconds or less and indicates adequate distal perfusion. Option B is incorrect because mild swelling that decreases with elevation is expected after casting; the nurse elevates the arm, applies ice, and continues neurovascular checks. Option D is incorrect because itching under a cast is common; the nurse teaches the client not to insert objects under the cast and to use cool air from a hair dryer for relief. Source: Ignatavicius & Workman, Medical-Surgical Nursing (compartment syndrome and cast care); Merck Manual Professional, Compartment Syndrome.